In the wireless communication, a carrier signal is usually not a sine wave with a single frequency due to the instability of the local oscillators of a transmitter and a receiver. For this reason, when the carrier frequency of a wireless communication system is relatively high, and when the wireless communication system uses a high-order modulation mode, the influence of phase noise is usually not to be ignored. Therefore, the receiver must estimate the phase noise introduced by the whole link and compensate the receiving signals which are influenced by the phase noise so as to achieve the purpose of accurately detecting the transmitted data symbol.
At present, there are mainly several types of methods for estimating phase noise, which are described as follows.
Method 1, a phase-locked loop is used to track phase noise, and a second-order phase-locked loop is usually used at present.
Method 2, the time for receiving signals is divided into a plurality of time slices, phase noise in each time slice is approximatively set to be constant, and the phase average in a specific time slice is acquired by an appropriate statistical algorithm.
Method 3, an interpolation-based algorithm: a specific frame structure is constructed, for example, both the head and the tail of each frame have pilot frequencies, the phase noise at the pilot frequency position of each data frame is estimated firstly, and the phase noise at the data symbol part in the frame is achieved through interpolation.
Method 4, a joint detection estimating algorithm based on channel and phase noise: this method is high in complexity and large in the time delay of signal processing.
As regards the above-mentioned Method 1, the phase-locked loop needs a certain capture time to lock the phase, as a result, the phase noise cannot be compensated in time.
As regards the above-mentioned Methods 2-4, the statistical property of the phase noise is needed, and the accuracy for estimating the phase noise is not high enough.